1. Field of the Invention
This invention relates to locks, specifically to an improved actuating mechanism for operating locks.
2. Background of the Related Art
To secure a door against undesirable or unwanted entry, the door is provided with a lock. The lock is intended to secure the door when closed until the lock is actuated to an unlocked status to allow the door to be moved to an open position. Typically, a door is fastened to a frame which defines an opening in a wall, fence, or other enclosure. This is done in a manner which allows the door to be moved with respect to the opening to permit access and then reposition the door quickly and easily while maintaining the door in alignment to reseal the opening. This may be accomplished by using hinges on one of the stiles of the frame, or the door may be located on rollers, or may hang on rollers or be otherwise movable.
To change the lock from a locked to an unlocked status, (or vice versa) many locks are actuated by a key on the exterior side of the door and a thumbturn (a small handle) on the interior side. In some cases it is desirable for the lock to be operated by a key on the inside of the door as well as the outside, particularly when securing the contents of a room is more important than ease of egress.
Due to increasing government regulation and concern over issues of life safety in a building occupied by the public or used for commercial purposes, the local authority with jurisdiction may deem it necessary to change a lock which is actuated by a key on the inside of a door to thumbturn operation or vice versa, depending on the use and occupancy requirements of the building. In some instances complying with a request to change a lock is difficult. For example, it is very common, particularly with glass doors, for a lock to be installed in the bottom edge of the door which extends a bolt into the floor to secure the opening. In this event, to change the function of a lock from one type of actuation to the other, it is frequently necessary to remove the door from its frame mounting in order to access the lock so that the change can take place.
Removing the door must also occur in the normal routine if rekeying the locks in glass doors so that they can be operated by a different key. To accomplish this a company specializing in the installation and repair of glass doors may be contracted to perform the task of removing the door so that a technician specializing in the installation and repair of locks can perform the task of rekeying the lock.
Once the door is removed it must be positioned in a stable manner with the bottom edge revealed. Next, it may be necessary to remove a plate which covers the setscrew that secures the key actuating mechanism (also called a key cylinder) into the lock case. With setscrew loosened, the cylinder is removed so that it can be rekeyed. Once this procedure is completed, these steps must be repeated in the reverse order to finish the job. This is not only inconvenient but also relatively expensive and very time consuming.
A removable core key cylinder, shown in FIG. 1, (also referred to as an interchangeable core cylinder) can be used to simplify rekeying a lock. This type of cylinder is a “core” that fits into a “housing” (not shown) that is installed in a lock in the same manner as any cylinder unit. The core 10 typically includes a control lug 12, a barrel 14 that receives a key (not shown), and a body 16. The control lug 12 is released by a special key (not shown), commonly referred to as a control key. The control key enables the layman to rekey the lock by removing the core 10 of the key assembly and then replace the core 10 with another operated by a different key without dismantling the lock or door assemblies. This simple method of rekeying the lock however is not available if the function of the lock must change from key actuation to thumbturn actuation or vice versa. This is because in a key operated cylinder, the special key is inserted in the keyway 18 (or key hole) located in the barrel 14. Conversely, in a thumbturn operated cylinder, a handle replaces the keyway. Since there is no keyway or provision in the front of a thumbturn cylinder to insert a control key, a thumbturn could not be removed by a control key. The present invention solves the problem of replacing a removable core key cylinder with a thumbturn.